As the GKN Aerospace incident moves from emergency response to investigation and potential enforcement, the adequacy of the facility’s compliance with each of these overlapping regulatory obligations will be a central question for federal, state, and local authorities.
On May 21, 2026, a 34,000-gallon storage tank at the GKN Aerospace facility in Garden Grove, California began leaking methyl methacrylate (MMA), a volatile and highly flammable industrial chemical used to manufacture high-strength acrylic plastics. GKN Aerospace makes advanced military and commercial transparencies, such as aircraft canopies, windshields, cabin windows, bullet-resistant glass, and spacecraft windows.
In polymer chemistry lingo, MMA is known as a monomer. Monomers are like individual links to a chain. Under the right conditions they link up (react) with each other to form long-chained polymers, or plastics. MMA is an unstable monomer that requires controlled storage conditions to avoid setting off a polymerization (chain) reaction.
According to early reports, the MMA tank at GKN Aerospace overheated. The cause of the overheating is not yet clear, but the overheating may have created conditions enabling the MMA to initiate polymerization, which in turn generated heat, which in turn generated pressure, activating the tank’s pressure-relief system and releasing MMA vapor into the atmosphere. Concerns about a runaway reaction, massive release, and explosion led the Orange County Fire Authority to order evacuation of approximately 40,000 residents and closure of thirteen schools.
Mr. Sherlock may be contacted at ssherlock@swlaw.com